Many metals and metal compounds are flammable. When ignited, a metal may act as the fire's fuel and may be oxidized by a number of elements and/or compounds. Most metals prone to ignite may produce fires of extremely high temperatures and may be difficult to extinguish. The classification for fires involving metals and/or metal compounds are commonly known as “Class D” fires. Examples of these metals include, but are not limited to, lithium, sodium, potassium, rubidium, cesium, francium, beryllium, titanium, uranium, and plutonium. Some metal compounds, such as, for example, alkyllithiums, Grignards and diethyizinc, are pyrophoric organometalic reagents. Most pyrophoric organometalic reagents may burn at high temperatures and may react violently with, for example, water, air, and/or other chemicals.
Because these materials react to produce extremely high temperature fires and are natural catalysts, they have the ability to extract oxidizers from their surrounding environment and/or from compounds normally used as fire extinguishing agents. These oxidizing agents are not necessarily oxygen-containing compounds. Many metals, such as, for example, magnesium, sodium, lithium, and potassium, once ignited, will burn in, for example, gases containing nitrogen, chlorine, fluorine, sulfur, and/or sulfur. The gases may disassociate common fire extinguishing agents, such as, for example, carbon dioxide and Halon® to free radicals needed to support their combustion.
One example of how reactive these metals are is demonstrated by the modern aircraft flare. This type of flare is not compounded from traditional oxidizers such as potassium nitrate or potassium chlorate, which are rich in oxygen, but are in fact a mixture of finely powdered magnesium and Teflon®. Teflon® is considered to be one of the least reactive materials known to man and contains no oxygen. Once ignited, however, Teflon® decomposes to release fluorine, which acts as its oxidizing agent. The reaction tends to be more vigorous and tends to produce temperatures hotter than would be possible with oxygen.
When water comes into contact with some of these metals, such as, for example, lithium, sodium, potassium, and magnesium, hydrogen gas is dissociated from the water and a hydroxide radical is formed. The hydrogen gas formed by this reaction is a very combustible gas and may be often ignited by heat generated by the decomposing metal/water reaction. In such reactions, a dangerous situation may result if certain chemicals used in fire extinguishers are applied to certain types (e.g., classes) of fires. In fact, some dangerous situations are sometimes associated with the above reactions. For example, some fire fighting training manuals include warnings such as, for example, the following warning: “It is vital to know what type of extinguisher you are using. Using the wrong type of extinguisher for the wrong type of fire can be life-threatening.”
When metals and/or metal compounds are shipped from one location to another, they may often be shipped in containers and/or on pallets with other types of freight, such as, for example, plastic parts and/or paper boxes. The resulting mixture of freight types, if involved in a fire, may likely require different types of fire extinguishing agents in order to effectively extinguish the different classes of fires (e.g., Class A, Class B, and/or Class D fires).
Fire extinguishing agents sometimes used to safely extinguish Class D fires (e.g., those types of fires sometimes associated with metals and/or metal compounds) may not be desirable for extinguishing other classes of fires. As a result, such agents may require adherence to special procedures for effective use, such as the following procedure for using an agent sold under the trade name, “Purple K®”: “Apply the dry powder. Completely cover the burning metal with a thin layer of powder. Once control is established, take a position that is in close range. Throttle the stream with the nozzle valve to produce a soft, heavy flow. Cover the metal completely with a heavy layer of powder. Be careful not to break the crust formed by the powder. Slowly open the nozzle of the extinguisher.”
When shipping a mixture of types of freight (e.g., metals and/or metal compounds, plastic materials, and/or paper boxes), however, it may not be possible to follow such rules, for example, because it may not be practical to orient the freight in a manner where freight containing metals and/or metal compounds would be positioned in such a way to allow the fire extinguishing agent (e.g., fire extinguishing powder) to cover all exposed sides of that type of freight. For example, if a container of metallic sodium were shipped, it might be loaded high on or in the middle of a built-up pallet load of other freight contained in cardboard boxes. As the cardboard boxes burn during a fire, the freight load might constantly shift and thereby re-expose the burning sodium following coverage with extinguishing powder. Further, because of sodium's low melting point, the sodium might simply melt and run out from under the powdered agent.
Freight shipments sometimes referred to as “Hazardous Freight” shipments may often include a mixture of types of materials. As a result, if such a freight shipment were to catch fire, it might generate various classes of fires (e.g., Class A, Class B, and/or Class D fires). No single conventional fire extinguishing agent, however, exists that is desirable for extinguishing all such classes of fires. In most situations, for example, attempting to extinguish a mixed class fire, including a Class D fire along with a Class A and/or a Class B fire, may be futile due, for example, to the differing needs of fire extinguishing agents for different fire classes. For example, if active elements such as Halon® and/or one of the known Halon® replacement agents are used to extinguish a Class D fire, a dangerous situation might result.
There may exist a need for a fire extinguishing agent that may be used to effectively and/or safely extinguish a fire including burning metals and/or metal compounds. Further, there may exist a need for a fire extinguishing agent that may be used to effectively and/or safely extinguish a fire including burning metals and/or metal compounds along with other types of burning materials.
The invention may seek to satisfy one or more of the above-mentioned needs. Although the present invention may obviate one or more of the above-mentioned needs, it should be understood that some aspects of the invention might not necessarily obviate them.